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Article

Spatial Pattern of Genetic Diversity in the Blood Fluke Aporocotyle argentinensis (Digenea, Aporocotylidae) from South American Hakes (Pisces: Merluccidae)

by
Marcelo E. Oliva
1,2,*,
Leyla Cárdenas
3,4,
Isabel M. Valdivia
5,
Paulina Bruning
4,6,
Luis Figueroa-Fabrega
5 and
Rubén Escribano
2
1
Instituto Ciencias Naturales Alexander von Humboldt, Universidad de Antofagasta, Antofagasta 1270300, Chile
2
Millenium Institute of Oceanography, Universidad de Concepción, Concepción 4070386, Chile
3
Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia 5110566, Chile
4
Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia 5090000, Chile
5
Laboratorio de Estudios Ecosistémicos—LECOS, Escuela de Ingeniería y Negocios, Universidad Viña del Mar, Viña del Mar 2520000, Chile
6
Ocean, Department of Biology, Université Laval, Québec, QC G1V 0A6, Canada
*
Author to whom correspondence should be addressed.
Diversity 2022, 14(9), 772; https://doi.org/10.3390/d14090772
Submission received: 31 July 2022 / Revised: 4 September 2022 / Accepted: 13 September 2022 / Published: 19 September 2022
(This article belongs to the Special Issue Diversity of Macroparasites in Marine Fishes)
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Abstract

:
Distribution of blood fluke Aporocotyle spp. parasitizing Merluccius species from the coasts of South America (Peru, Chile and Argentina) constitutes an excellent opportunity to evaluate the geographical amplitude in which a parasite can exploit the same host species. Phylogenetic analyses (partial sequences of SSU rDNA, LSU rDNa, and cox1 gene) were performed to characterize the genetic lineage of Aporocotyle species described from South American Hake: Merluccius australis, M. gayi, and M. hubbsi. The Phylogenetic analyses (SSUrDNA and LSUrDNA) revealed an absence of genetic variability in Aporocotyle obtained over a gradient of 6800 km, covering two oceans and three closely related hosts. Consequently, the species infecting Merluccius spp. in South America is Aporocotyle argentinensis Smith 1969, by priority law. Phylogeographic analysis suggests a pattern of spatial differentiation and genetic population structure associated with the geographical distribution of the host’s species. A specimen with a haplotype found in M. gayi was collected from M. australis from Puerto Montt, and three worms (from Coquimbo, Constitución and Talcahuano, host M. gayi) harbored a haplotype found in M. australis + M. hubbsi, suggesting that the gene flow between different hosts and geographical distributions occurs when the distribution of adequate hosts overlaps, avoiding speciation in blood flukes from South American hakes.

1. Introduction

Systematic parasitology is traditionally based on morphological traits. However, problems that potentially confound the use of morphology in parasites include the challenges of consistent specimen preservation, plasticity of features depending on hosts or other environmental factors, and morphological convergence [1]. Molecular markers can be excellent tools to show the actual level of biodiversity in parasites [2]. The use of these tools in parasite systematics revealed the existence of cryptic species, i.e., two or more distinct species that are erroneously classified (and hidden) under one species name [3]. By contrast, lineages identified as independent species can be correctly recognized as synonymous [4,5]. As a consequence, the establishment of the actual number of species in a given host-parasite system is an urgent requirement for a theoretical framework of the study of diversity, ecology, evolution, and co-speciation in parasites.
Eighteen species are described in the genus Aporocotyle (Digenea: Aporocotylidae Odhner, 1912) [6] that infect the heart, bulbous arteriosus, and blood vessels of marine fishes of five teleost orders (Gadiformes, Ophidiiformes, Perciformes, Pleuronectiformes, and Scorpaeniformes) from the Atlantic, Pacific, Antarctic, and Indian oceans and the Japan and Baltic seas. Notably, five of the species are described from five species of Merluccius: Aporocotyle spinosicanalis from M. merluccius; A. argentinensis from M. hubbsi; A. margolisi from M. productus; A. wilhelmi from M. gayi; and A. australis from M. australis (Gadiformes). Aporocotyle species parasitizing hakes worldwide are apparently highly host specific. Recently, a possible cospeciation of members of Aporocotyle with their hosts was suggested, at least for members of the genus Merluccius [6]. In addition, of the 18 recognized species in the genus, only two are registered from more than one host species: Aporocotyle simplex in three species of flatfishes of the subfamily Pleuronectinae [7] and Aporocotyle garciai described from two Ophiididae: Genypterus sp. from Perú and Hoplobrotula armata from Japan [8,9].
Aporocotyle spp. parasitizing Merluccius species from the Pacific and Atlantic coasts of South America (Peru, Chile, and Argentina) constitute an excellent opportunity to evaluate the actual level of genetic variability in a marine parasite and the geographical amplitude in which a parasite can exploit the same host species. Along the Pacific coast of South America, two species of hake are found: Merluccius gayi with two populations, a northern population (Peruvian hake) from the Gulf of Guayaquil to central Peru [10] and a southern population (Chilean hake) from northern to southern Chile; this hake is the host for Aporocotyle wilhelmi Villalba and Fernández, 1986. The second species, Merluccius australis, is found in southern Chile, overlapping with M. gayi, and is the host for Aporocotyle australis Fernández and Durán, 1985 (Figure 1A). Along the Atlantic coast of South America, M. australis reached as north as ≈40°S, whereas a second species from the Atlantic, Merluccius hubbsi, overlap in the northern limit of distribution of M. australis in the Atlantic (Figure 1A). M. hubbsi is the host for A. argentinensis Smith, 1969.
Our goals were to characterize the phylogenetic relationship among Aporocotyle species in three Merluccius species (M. hubbsi, M. gayi, and M. australis) from the Atlantic (Argentina and Falkland Islands/Islas Malvinas) and Pacific coasts (Chile and Perú) of South America, based on partial sequences of two molecular markers (SSU rDNA and LSU rDNA), and to evaluate the spatial distribution of the identified lineages of Aporocotyle in South American hakes, based on cox1 gene.

2. Materials and Methods

Samples

In total, 331 partial sequences (98 SSU rDNA, 57 LSU rDNA, and 176 cox1) belonging to three nominal species of Aporocotyle were analyzed. The parasites were obtained for hakes M. gayi and M. australis from Chile (six localities), M. gayi from Peru (one locality), M. australis and M. hubbsi from Argentina (two localities), and M. hubbsi from Falkland Islands/Islas Malvinas (Table 1, Figure 1A). Fish were obtained from commercial catches of hakes. To extract genomic DNA, a DNA E.Z.N.A kit (Omega Bio-Tek, Inc., Atlanta, GA, USA) was used. Specimens were sequenced and amplified using described protocols for SSU rDNA, LSU rDNA, and cox1 gene [11,12,13]. The PCR products were purified using a PCR E.Z.N.A. Cycle Pure Kit (Omega Bio-Tek, Atlanta, GA, USA) and sequenced in an automated capillary electrophoresis sequencer ABI 3730XL (Macrogen Inc., Seoul, Korea). To minimize sequencing errors, both strands were sequenced from all genes for each individual sample. All new sequences were deposited in Genbank (Accession codes available in Supplementary Material Table S1). Sequences were edited and aligned using Geneious 2020.2.3 (https://www.geneious.com, accessed on 2 June 2022) [14].
For the phylogenetic analyses, sequences available at GenBank for members of Aporocotyle were included, and sequences from Psettarium nolani (Aporocotylidae) were used as the external group (Supplementary Material Table S1).
The phylogenetic trees for nuclear genes were inferred by the maximum likelihood (ML) criteria using MEGA v. 7 [15], and the HKY model yielded the best fit for the three genes [16]. To assess the support for individual nodes, a bootstrap (1000 replicates) analysis was performed. The phylogenetic trees were inferred by Bayesian inference (BI; MrBayes v3.2) [17] and were conducted applying Markov Chains and running 10,000,000 generations, sampling each of 200 generations. Trees for ML and BI show the same topology.
Bayesian phylogenetic analyses were conducted using four simultaneous Markov Chains. The first 25% generations (burning) were discarded.
To analyze the spatial genetic structure of Aporocotyle from South American hakes, a phylogeographic analysis using cox1 partial sequences was performed. Arlequin v. 3.11 [18] allows the calculation of the number of haplotypes, number of polymorphic sites, haplotype diversity, nucleotide diversity, as well as a hierarchical analysis of molecular variance (Table 2). Finally, the genealogical relationships among haplotypes were assessed with a haplotype network (Figure 1B) constructed using a median-joining algorithm, as implemented in network 4.201 [19]. We applied a maximum parsimony algorithm to simplify the complex branching pattern and to represent all the most parsimonious intraspecific phylogenies [20].

3. Results

For the SSU rDNA, a fragment of 411 bp was sequenced from each one of the 98 analyzed specimens. The tree reconstruction, including A. spinosicanalis (Figure 2A), a parasite of the European hake Merluccius merluccius, showed a unique clade that included all specimens from the three hosts and all studied localities, with a bootstrap support of 100% for ML and 1 for BI. The absence of genetic variation from worms in the three host’s species strongly supports that the three described species of Aporocotyle from Merluccius spp. along the South American coast constitute a unique genetic lineage (Figure 2), but the ML support for the clade of Aporocotyle from South American hakes shows a weak support (ML = 70%), but it was fully supported by BI (PP = 1).
For the LSU rDNA gene, a fragment of 913 bp was sequenced from 57 specimens of Aporocotyle spp. Sequences of LSU rDNA genes for three Aporocotyle species available in Genbank were incorporated in the analysis. The topology of the phylogenetic tree reconstruction (Figure 2B) was consistent with the SSU rDNA phylogenetic tree, node support was always 100% (ML), and posterior probability (PP) = 1 (BI). The genetic distance between our samples and A. argentinensis (GenBank JX094803) was 0.0%.
For the cox1 gene, a fragment of 677 bp was sequenced from 176 specimens of Aporocotyle spp.
The haplotype network, based on cox1 partial sequences, showed a clear pattern in the spatial distribution of the genetic lineages of Aporocotyle (Figure 1B). Haplotype H1 was found primarily, at higher frequency, in worms from M. gayi, but one worm collected from M. australis at Puerto Montt also showed this haplotype. The frequency of haplotype H5 was high in worms from M. australis and M. hubbsi; however, three individuals collected from M. gayi showed this haplotype, one each from Coquimbo, Talcahuano, and Constitution. From each one of the primary haplotypes, an upsurge of low frequency haplotypes was observed, distant by only one mutation step. Some haplotypes from M. hubbsi differed in one mutational step from those from M. australis.
In summary, geographically, the haplotype relationships among parasites showed a concordant pattern with the current distribution of the host species but also suggested a genetic connectivity across regions (Figure 1B).
The intraspecific genetic variation was analyzed using a data set of partial sequences of cox1 and showed a clear pattern of spatial differentiation with a global FST of 0.63 (p-value < 0.0001). The pairwise FST analysis (Table 3) revealed that worms parasitizing M. australis from southern Chile (Puerto Montt, Guaitecas, Aysén) and Argentina (Puerto Madryn) and M. hubbsi from Mar del Plata do not differ significantly. However, worms parasitizing populations of M. gayi from Chile (Coquimbo, Duao, Constitución and Talcahuano) and those from Peru (Callao) were genetically similar. Both geographical groups were coincident with the spatial distribution of the host species, with values of pairwise FST among them ranging from 0.437 to 0.928 (Table 3).
The substitution saturation test [21], implemented in DAMBE V 7.3.11 software, showed no evidence of saturation substitution in any of the studied genes.

4. Discussion

The described species of Aporocotyle from hakes of South America are A. argentinensis, a parasite of M. hubbsi from Argentina, A. australis from M. australis in southern Chile, and A. wilhelmi from M. gayi caught in Concepcion Bay, central Chile [6]. Our results, obtained from samples along a geographical gradient of approximately 6800 km along the Pacific and Atlantic coast of South America, including the Falkland Islands/Islas Malvinas, were highly consistent and supported the presence of a unique genetic lineage, that by priority law should correspond to A. argentinensis. No variation was found in the phylogenetic analysis of both nuclear genes for samples of Aporocotyle parasitizing the three hake species, M. gayi, M. australis, and M. hubbsi. Recently [22], the analysis of 252 studies, published between 2011 to 2015 and regarding the molecular approach to trematode systematics, showed that ribosomal RNA (rRNA) genes (LSU, SSU, ITS 1, and ITS 2) were widely used in taxonomy, life cycle studies, and species diagnosis.
The existence of cryptic species in Digenea, i.e., species morphologically indistinguishable but genetically different, is well documented [5], mainly due the development of molecular tools. The report of host-induced variability, impact of the site of infection in the host, as well as the effect of intensity of infection are also well documented [23], but proof of genetic identity are rare, and our results support the argument that apparent host specificity is not a reliable criterion to delineate species [5].
The pattern of genetic similarity on a wide geographic scale was reported and linked to marine species that have a high dispersal potential [24]. The absence of genetic difference in the Aporocotylid Cardicola forsteri parasitizing two related tuna from Australia and Mexico (Thunnus maccoyi from a wild population at Cabbage Patch, South Australia and Thunnus thynus from a farm in Spain (Mediterranean sea)) was demonstrated [25], and in a similar way, the absence of genetic and morphological variability in some species of Digenea from the Barrier Coral Reef (Australia) and French Polynesia, 6000 km apart, have been described [26]. Along the Southeastern Pacific, no genetic variability was found in Proctoeces humboldti (as Proctoeces cf. lintoni) from two localities 2000 km apart [27].
For the mitochondrial cox1 gene, we recovered two central haplotypes separated by one mutational step. These haplotypes were more frequently founded in a spatial scale associated with the geographical distribution of hakes, but it is important to note that some Aporocotyle specimens collected from M. gayi shared the same haplotype with those specimens collected from M. australis in Puerto Montt (see Figure 1B) where the two host species overlap. As suggested [6], body size, length of the esophagus, anterior and posterior caeca, size of the cirrus sac, and size of the ovary among other metrics are affected by the host distribution and, consequently, are of doubtful value in the taxonomy of Aporocotyle. The ratio between esophagus length/total length and testis number was defined among the taxonomic characters considered in the description of the Chilean species of Aporocotyle and in the definition of their evolutionary series [28]. However, it was demonstrated that this ratio changes allometrically during the life span, at least for Aporocotyle simplex, and the number of testis is also a taxonomic character of questionable relevance because the number is highly variable and the degeneration of testis in larger specimens is well documented [29]. Our results strongly suggest that the described species of Aporocotyle from South American hakes belong to a single species, Aporocotyle argentinensis, and are a new evidence of the usefulness of molecular tools to obtain the correct species diagnosis in digenean parasites [30].
The distribution of each host species is definitively narrower than the parasite distribution. This does not explain the absence of genetic variability for SSU rDNA and LSU rDNA, but the gene flow can be explained for the overlap of the geographic distribution of M. hubbsi and M. australis in the South Atlantic Ocean and between M. australis and Merluccius gayi in the South Pacific Ocean. It is important to note that the nuclear markers used here may not be variable enough, but the addition of the mitochondrial gene cox1 to the analysis supported the results of similarity. Although, it also showed evidence of a trend of an incipient speciation process that is not backed up statistically.
Parasites normally have shorter generational times than their hosts; therefore, genetic differentiation and demographic changes may be detected sooner in parasites because more mutations are fixed over time, leading to a more rapid lineage sorting [31].
Although the studied hosts are well resolved species, members of Aporocotyle from South American hake did not follow a similar pattern, suggesting that genetic diversification in parasites responds not only to the evolutionary history of their definitive hosts but also intermediate hosts [32]. Additional factors such as complexity in the life cycle and environmental factors are also important. An interesting result was given by the significant differences caused by samples from Mar del Plata (Table 3).This zone corresponds to a transitional biogeographical area that responds to the particular oceanographic patterns where the oceanographic front of Peninsula Valdes influences the diversity of fish species [33,34], which could be reflected in the phylogeographic patter we found. In other words, specimens from Mar del Plata have a spatial genetic structure different from the other localities.
At the population level, the mitochondrial cox1 revealed the occurrence of low gene flow, supported by high values of FST, between parasite populations of the three host’s species, probably preventing the generation of isolated new lineages. In addition, for the cox1 gene, we recovered two shared haplotypes, separated by one mutational step. These haplotypes are more frequently found in a spatial scale associated with the geographical distribution of hakes, but it is important to note that some Aporocotyle specimens collected from M. gayi shared the same haplotype with those specimens collected in M. australis.
A highly mobile host is a potential explanation for the maintenance of gene flow among parasite populations, in addition to a wide geographical distribution for the definitive and intermediate hosts. Moreover, in members of Aporocotyle, the absence of a second intermediate host and the direct infection of the definitive host by the cercarial stage [35,36] eliminate the trophic link between the second intermediate host and its definitive host. The intermediate host for Aporocotyle spp. parasitizing hakes in South America are unknown, but terebellid polychaetes has been considered the major host group for marine aporocotylids [35].
Our results emphasize the importance of overlap in geographic host distributions, as a force that can explain the spatial distribution of the genetic diversity in a blood parasite (Aporocotyle spp.) in different biogeographical regions. We showed the importance of studying genetic identity for morphologically different morphotypes associated with parasites of different but closely related host species. Consequently, apparent host specificity, in some cases, is not a reliable criterion to delineate species [5].

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/d14090772/s1, Table S1: Host species, sequence name, locality, and accesion code for gene bank. References [6,37,38,39,40,41] are cited in supplementary material.

Author Contributions

M.E.O., L.C. and I.M.V. conceived and designed the study; M.E.O., I.M.V., L.F.-F. and R.E. carried out the field work; L.C., I.M.V. and P.B. performed molecular analyses. Additional analyses were performed by R.E. and M.E.O.; M.E.O., L.C. and I.M.V. wrote the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

Grant FONDECYT 1140173 (MEO) funded this research. Proyecto Desarrollo Institucional (FDI) del MINEDUC UVM21101-Chile (IMV), Millennium Institute of Oceanography (IMO-Chile), IC120019 (RE) and FONDAP IDEAL 15150003 (LC) also provided support.

Institutional Review Board Statement

This study did not consider experiments with live animals. All fishes were obtained from commercial catches and none of the species are subject to conservation measures. Commercial fishermen follow national regulations concerning these fisheries.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data available as supplementary material.

Acknowledgments

Special thanks are offered to Juan T. Timi, Universidad Nacional de Mar del Plata, who is thanked for the use of laboratory facilities, and Paul Brickle and the fisheries team of the South Atlantic Environmental Research Institute, Falkland Islands/Islas Malvinas (SAERI) are thanked for their assistance and use of laboratory facilities.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Perkins, S.L.; Martinsen, E.S.; Falk, B.G. Do molecules matter more than morphology? Promises and pitfalls in parasites. Parasitology 2011, 138, 1664–1674. [Google Scholar] [CrossRef] [PubMed]
  2. Criscione, C.D.; Poulin, R.; Blouin, M.S. Molecular ecology of parasites: Elucidating ecological and microevolutionary processes. Mol. Ecol. 2005, 14, 2247–2257. [Google Scholar] [CrossRef] [PubMed]
  3. Nadler, S.A.; Pérez-Ponce de León, G. Integrating molecular and morphological approaches for characterizing parasite cryptic species: Implications for parasitology. Parasitology 2011, 138, 1688–1709. [Google Scholar] [CrossRef]
  4. Martínez-Aquino, A.; Ceccarelli, F.S.; Pérez-Ponce de León, G. Molecular phylogeny of the genus Margotrema (Digenea: Allocreadiidae), parasitic flatworms of goodeid freshwater fishes across central Mexico: Species boundaries, host-specificity, and geographical congruence. Zool. J. Linn. Soc. 2013, 168, 1–16. [Google Scholar] [CrossRef]
  5. Presswell, B.; Bennett, J. Galactosomum otepotiense n.sp. (Trematoda: Heterophydae) infecting four different species of fish-eating birds in New Zealand: Genetically identical but morphologically variable. J. Helminthol. 2020, 94, e86. [Google Scholar] [CrossRef] [PubMed]
  6. Hernández-Orts, J.S.; Hernández- Mena, D.L.; Alama-Bermejo, G.; Kuchta, R.; Jacobson, K.C. Morphological and molecular characterization of Aporocotyle margolisi Smith, 1967 (Digenea: Aporocotylidae) from the North Pacific hake Merluccius productus (Ayres) (Gadiformes: Merluccidae) off Oregon, USA. Syst. Parasitol. 2017, 94, 819–829. [Google Scholar] [CrossRef]
  7. Smith, J.W. On Aporocotyle argentinensis n. sp. (Digenea: Sanguinicolidae) from Merluccius hubbsi, and the phylogeny of Aporocotyle Odhner, 1900 in Hake. J. Helminthol. 1969, 43, 371–382. [Google Scholar] [CrossRef]
  8. Tantaléan, M.; Martínez, R. Aporocotyte garciai (Digenea Sanguinicolidae), parasito de Genypterus sp. de la costa Peruana. Parasit. al Dia 1990, 14, 67–69. [Google Scholar]
  9. Kamegai, S.; Machida, M.; Kuramochi, T. Two Blood Flukes from Deep-sea Fishes of Suruga Bay. Bull. Natl. Sci. Mus. Tokyo Ser. A 2002, 28, 29–34. [Google Scholar]
  10. Pitcher, T.J.; Alheit, J. What Makes a Hake? A Review of the Critical Biological Features That Sustain Global Hake Fisheries. In Hake: Fisheries, Ecology and Markets; Pitcher, T.J., Alheit, J., Eds.; Chapman & Hall: Salisbury, UK, 1995; pp. 1–14. [Google Scholar]
  11. Hall, K.A.; Cribb, T.H.; Barker, S.C. V4 region of small subunit rDNA indicates polyphyly of the Fellodistomidae (Digenea) which is supported by morphology and life-cycle data. Syst. Parasitol. 1999, 43, 81–92. [Google Scholar] [CrossRef]
  12. Chisholm, L.; Morgan, J.; Adlard, R.; Whittington, I. Phylogenetic analysis of the Monocotylidae (Monogenea) inferred from 28S rDNA sequences. Int. J. Parasitol. 2001, 31, 1537–1547. [Google Scholar] [CrossRef]
  13. Leung, T.; Poulin, R.; Keeney, D. Accumulation of diverse parasite genotypes within the bivalve second intermediate host of the digenean Gymnophallus sp. Int. J. Parasitol. 2009, 39, 327–331. [Google Scholar] [CrossRef] [PubMed]
  14. Kearse, M.; Moir, R.; Wilson, A.; Stones-Havas, S.; Cheung, M.; Sturrock, S.; Buxton, S.; Cooper, A.; Markowitz, S.; Duran, C.; et al. Geneious Basic: An integrated and extendable desktop software platform for the organization and analysis of sequence data. Bioinformatics 2012, 28, 1647–1649. [Google Scholar] [CrossRef] [PubMed]
  15. Kumar, S.; Stecher, G.; Tamura, K. MEGA7: Molecular Evolutionary Genetic Analysis. V. 7.0 for bigger datasets. Mol. Biol. Evol. 2016, 33, 1870–1874. [Google Scholar] [CrossRef] [PubMed]
  16. Hasegawa, M.; Kishino, H.; Yano, H. Dating of the human-ape splitting by a molecular clock of mitochondrial DNA. J. Mol. Evol. 1985, 22, 160–174. [Google Scholar] [CrossRef]
  17. Ronquist, F.; Teslenko, M.; Van Der Mark, P.; Ayres, D.L.; Darling, A.; Höhna, S.; Larget, B.; Liu, L.; Suchard, M.A.; Huelsenbeck, J.P. MrBayes 3.2: Efficient Bayesian phylogenetic inference and model choice across a large model space. Syst. Biol. 2012, 61, 539–542. [Google Scholar] [CrossRef]
  18. Excoffier, L.; Laval, G.; Schneider, S. Arlequin (version 3.0): An integrated software package for population genetics data analysis. Evol. Bioinform. Online 2005, 1, 47–50. [Google Scholar] [CrossRef]
  19. Bandelt, H.J.; Forster, P.; Rohl, A. Median-joining networks for inferring intraspecific phylogenies. Mol. Biol. Evol. 1999, 16, 37–48. [Google Scholar] [CrossRef]
  20. Polzin, T.; Daneschmand, S.V. On Steiner trees and minimum spanning trees in hypergraphs. Oper. Res. Lett. 2003, 31, 12–20. [Google Scholar] [CrossRef]
  21. Xia, X.; Xie, Z.; Salemi, M.; Chen, L.; Wang, Y. An index of substitution saturation and its applications. Mol. Phylogenet. Evol. 2003, 26, 1–7. [Google Scholar] [CrossRef]
  22. Blasco-Costa, I.; Cutmore, S.C.; Miller, T.L.; Nolan, M.J. Molecular approaches to trematode systematics: ‘best practice’ and implications for future study. Syst. Parasitol. 2016, 93, 295–306. [Google Scholar] [CrossRef] [PubMed]
  23. Oliva, M.; Zegers, J. Variaciones intraespecíficas del adulto de Proctoeces lintoni Siddiqi & Cable (Trematoda: Fellodistomidae) en hospedadores vertebrados e invertebrados. Stud. Neotrop. Fauna Environ. 1988, 23, 189–195. [Google Scholar]
  24. Palm, H.W.; Waeschenbach, A.; Littlewood, D.T.J. Genetic diversity in the trypanorhynch cestode Tentacularia coryphaenae Bosc, 1797: Evidence for a cosmopolitan distribution and low host specificity in the teleost intermediate host. Parasitol. Res. 2007, 101, 153–159. [Google Scholar] [CrossRef] [PubMed]
  25. Aiken, H.M.; Bott, N.J.; Mladineo, I.; Montero, F.E.; Nowak, B.; Hayward, C.J. Molecular evidence for cosmopolitan distribution of platyhelminth parasites of tunas (Thunnus spp.). Fish Fish. 2007, 8, 167–180. [Google Scholar] [CrossRef]
  26. Lo, C.M.; Morgan, J.A.T.; Galzin, R.; Cribb, T.H. Identical digeneans in coral reef fishes from French Polynesia and the Great Barrier Reef (Australia) demonstrated by morphology and molecules. Int. J. Parasitol. 2001, 31, 1573–1578. [Google Scholar] [CrossRef]
  27. Valdivia, I.M.; Cárdenas, L.; González, K.; Jofré, D.; George-Nascimento, M.; Guiñez, R.; Oliva, M.E. Molecular evidence confirms that Proctoeces humboldti and Proctoeces chilensis (Digenea: Fellodistomidae) are the same species. J. Helminthol. 2010, 84, 341–347. [Google Scholar] [CrossRef]
  28. Villalba, J.; Fernández, C. Tres nuevas especies de Aporocotyle Odhner, 1900 (Digenea: Sanguinicolidae) parasitas de Genypterus spp. en Chile (Pisces. Ophiididae). Rev. Biol. Mar. 1986, 22, 125–139. [Google Scholar]
  29. Thulin, J. A redescription of the fish blood-fluke Aporocotyle simplex Odhner, 1900 (Digenea, Sanguinicolidae) with comments on its biology. Sarsia 1980, 65, 35–48. [Google Scholar] [CrossRef]
  30. Bray, R.B.; Cutmore, S.C.; Cribb, T.H. A paradigm for the recognition of cryptic trematode species in tropical Indo-West Pacific fishes: The problematic genus Preptetos (Trematoda: Lepocreadiidae). Int. J. Parasitol. 2022, 52, 169–203. [Google Scholar] [CrossRef]
  31. Huyse, T.; Audenaert, V.; Volckaert, F.A.M. Speciation and host-parasite relationships in parasite genus Gyrodactylus (Monogenea, Platyhelminthes) infecting gobies of the genus Pomatoschistus (Gobiidae, Teleostei). Int. J. Parasitol. 2003, 33, 1679–1689. [Google Scholar] [CrossRef]
  32. Johnson, K.P.; Adams, R.J.; Page, R.D.M.; Clayton, D.H. When Do Parasites Fail to Speciate in Response to Host Speciation? Syst. Biol. 2003, 52, 37–47. [Google Scholar] [CrossRef] [PubMed]
  33. Alemany, D.; Acha, E.M.; Iribarne, O. The relationship between fronts and fish diversity in the Patagonian Shelf Ecosystem. J. Biogeogr. 2009, 36, 2111–2124. [Google Scholar] [CrossRef]
  34. Wieters, E.A.; McQuaid, C.; Palomo, G.; Pappalardo, P.; Navarrete, S.A. Biogeographical Boundaries, Functional Group Structure and Diversity of Rocky Shore Communities along the Argentinean Coast. PLoS ONE 2012, 7, e49725. [Google Scholar] [CrossRef] [PubMed]
  35. Cribb, T.H.; Adlard, R.D.; Hayward, C.J.; Botte, N.J.; Ellis, D.; Evans, D.; Nowak, B.F. The life cycle of Cardicola forsteri (Trematoda: Aporocotylidae), a pathogen of ranched southern bluefin tuna, Thunnus maccoyi. Int. J. Parasitol. 2011, 41, 861–870. [Google Scholar] [CrossRef]
  36. Koei, M. The redia, cercaria and early stages of Aporocotyle simplex Odhner, 1900 (Sanguinicolidae)—A digenetic trematode which has a polychaete annelid as the only intermediate host. Copeia 1982, 21, 115–145. [Google Scholar]
  37. Cribb, T.H.; Bray, R.A.; Littlewood, D.T.J.; Pichelin, S.P.; Herniou, E.A. The Digenea. In Interrelationships of the Platyhelminthes; Littleworod, D.T.J., Bray, R.A., Eds.; Taylor and Francis: London, UK, 2001; pp. 168–185. [Google Scholar]
  38. Olson, P.D.; Cribb, T.H.; Tkach, V.V.; Bray, R.A.; Littlewood, D.T.J. Phylogeny and classification of the Digenea (Platyhelmithes: Trematoda). Int. J. Parasitol. 2003, 33, 733–755. [Google Scholar] [CrossRef]
  39. Snyder, S.D.; Loker, E.S. Evolutionary relationships among the Schistosomatidae (Platyhelminthes: Digenea) and an Asian origin for Schistosoma. J. Parasitol. 2000, 86, 283–288. [Google Scholar] [CrossRef]
  40. Santoro, M.; Cipriani, P.; Pankov, P.; Lawton, S.P. Aporocotyle michaudi n. sp. (Digenea: Aporocotylidae) from the emerald rock cod, Trematomus bernacchii (Teleostei: Perciformes) in Antarctica. Parasitol. Int. 2015, 64, 324–329. [Google Scholar] [CrossRef]
  41. Lockyer, A.E.; Olson, P.D.; Littlewood, D.T.J. Utility of complete large and small subunit rRNA genes in resolving the phylogeny of the Neodermata (Platyhelminthes): Implications and a review of the cercomer theory. Biol. J. Linn. Soc. Lond. 2003, 78, 155–171. [Google Scholar] [CrossRef] [Green Version]
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Figure 1. Host distribution in South America (dashed area) (A) and mitochondrial cox1 haplotype network showing the 21 haplotypes identified in three species of hakes (B). Haplotypes are colored by the locality where the host were obtained. Size of circles is proportional to the number of individuals showing that haplotype. Code for localities: 1 = Callao, 2 = Coquimbo, 3 = Duao, 4 = Constitución, 5 = Talcahuano, 6 = Puerto Montt, 7 = Guaitecas, 8 = Puerto Madryn, 9 = Mar del Plata.
Figure 1. Host distribution in South America (dashed area) (A) and mitochondrial cox1 haplotype network showing the 21 haplotypes identified in three species of hakes (B). Haplotypes are colored by the locality where the host were obtained. Size of circles is proportional to the number of individuals showing that haplotype. Code for localities: 1 = Callao, 2 = Coquimbo, 3 = Duao, 4 = Constitución, 5 = Talcahuano, 6 = Puerto Montt, 7 = Guaitecas, 8 = Puerto Madryn, 9 = Mar del Plata.
Diversity 14 00772 g001
Diversity 14 00772 g002 550
Figure 2. Molecular phylogeny of Aporocotyle spp. parasitizing Merluccius spp. from South America based on the SSU rDNA gene (A) and LSU rDNA gene (B). BI support value above and ML support below the node.
Figure 2. Molecular phylogeny of Aporocotyle spp. parasitizing Merluccius spp. from South America based on the SSU rDNA gene (A) and LSU rDNA gene (B). BI support value above and ML support below the node.
Diversity 14 00772 g002
Table
Table 1. The South American species of the genus Merluccius studied, locality, geographic coordinates, and host sample size.
Table 1. The South American species of the genus Merluccius studied, locality, geographic coordinates, and host sample size.
HostLocalitySWN
Merluccius gayiCallao (1)12°03′50″77°08′58″10
Coquimbo (2)29°57′37″71°20′19″20
Duao (2)34°53′58″72°10′59″15
Constitución (2)35°18′59″72°25′43″20
Talcahuano (2)36°43′52″73°07′39″110
Merluccius australisPuerto Montt (2)41°28′39″72°56′44″45
Guaitecas Island (2)43°52′43″73°44′55″38
Puerto Madryn (3)42°46′10″65°01′18″20
Merluccius hubbsiMar del Plata (3)38°04′25″57°30′50″5
Falkland Islands /Islas Malvinas (4)51°40′58″57°40′44″12
1: Perú, 2: Chile; 3: Argentina, 4: UK/Argentina.
Table
Table 2. Mitochondrial cox1 diversity for Aporocotyle by host and locality. Np = number of parasites analyzed; Nhap = number of haplotypes; S = number of polymorphic sites; He = haplotype diversity; π = nucleotide diversity; k = mean number of pairwise differences. Standard deviations (SD) are also given.
Table 2. Mitochondrial cox1 diversity for Aporocotyle by host and locality. Np = number of parasites analyzed; Nhap = number of haplotypes; S = number of polymorphic sites; He = haplotype diversity; π = nucleotide diversity; k = mean number of pairwise differences. Standard deviations (SD) are also given.
HostLocationNpNhapSHe ± SDπ ± SDk ± SD
M. gayiCallao510000
Coquimbo15540.48 ± 0.150.00115 ± 0.000990.7809 ± 0.6012
Duao17320.23 ± 0.130.00035 ± 0.000470.2353 ± 0.2857
Constitución22430.26 ± 0.120.00040 ± 0.000510.2727 ± 0.3076
Talcahuano9210.22 ± 0.170.000328 ± 0.000480.2222 ± 0.2880
Total 68990.27 ± 0.070.00052 ± 0.000570.3443 ± 0.34692
M. australisPuerto Montt31540.25 ± 0.100.00038 ± 0.000490.2581 ± 0.2948
Guaitecas Islands22430.26 ± 0.120.0004 ± 0.000510.2727 ± 0.3076
Puerto Madryn23210.09 ± 0.080.00013 ± 0.000270.0869± 0.1640
Total 76980.20 ± 0.060.00031 ± 0.000420.2105 ± 0.2586
M. hubbsiMar del Plata32640.58 ± 0.090.00108 ± 0.000920.7278 ± 0.5571
Whole data set 17621180.62 ± 0.030.04369 ± 0.035320.7865 ± 0.5745
Table
Table 3. Pairwise FST analysis among sampled localities (below diagonal). P-values above the diagonal. Significant values (p < 0.001 Bonferroni corrections) after 1000 permutations. Code for localities: 1 = Callao, 2 = Coquimbo, 3 = Duao, 4 = Constitución, 5 = Talcahuano, 6 = Puerto Montt, 7 = Guaitecas, 8 = Puerto Madryn, 9 = Mar del Plata.
Table 3. Pairwise FST analysis among sampled localities (below diagonal). P-values above the diagonal. Significant values (p < 0.001 Bonferroni corrections) after 1000 permutations. Code for localities: 1 = Callao, 2 = Coquimbo, 3 = Duao, 4 = Constitución, 5 = Talcahuano, 6 = Puerto Montt, 7 = Guaitecas, 8 = Puerto Madryn, 9 = Mar del Plata.
123456789
1 0.5240.9990.9990.9990.0000.0000.0000.000
2−0.014 0.3940.4180.7620.0000.0000.0000.000
3−0.078 0.005 0.9990.9990.0000.0000.0000.000
4−0.071 −0.006 −0.025 0.9990.0000.0000.0000.000
5−0.078 −0.039 −0.044 −0.064 0.0000.0000.0000.000
60.792 0.638 0.754 0.7300.727 0.9990.3890.006
70.796 0.6250.754 0.730 0.726 −0.018 0.3630.031
80.928 0.7350.8520.8210.858 −0.0004 0.004 0.003
90.561 0.437 0.561 0.548 0.502 0.091 0.0750.146
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Oliva, M.E.; Cárdenas, L.; Valdivia, I.M.; Bruning, P.; Figueroa-Fabrega, L.; Escribano, R. Spatial Pattern of Genetic Diversity in the Blood Fluke Aporocotyle argentinensis (Digenea, Aporocotylidae) from South American Hakes (Pisces: Merluccidae). Diversity 2022, 14, 772. https://doi.org/10.3390/d14090772

AMA Style

Oliva ME, Cárdenas L, Valdivia IM, Bruning P, Figueroa-Fabrega L, Escribano R. Spatial Pattern of Genetic Diversity in the Blood Fluke Aporocotyle argentinensis (Digenea, Aporocotylidae) from South American Hakes (Pisces: Merluccidae). Diversity. 2022; 14(9):772. https://doi.org/10.3390/d14090772

Chicago/Turabian Style

Oliva, Marcelo E., Leyla Cárdenas, Isabel M. Valdivia, Paulina Bruning, Luis Figueroa-Fabrega, and Rubén Escribano. 2022. "Spatial Pattern of Genetic Diversity in the Blood Fluke Aporocotyle argentinensis (Digenea, Aporocotylidae) from South American Hakes (Pisces: Merluccidae)" Diversity 14, no. 9: 772. https://doi.org/10.3390/d14090772

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